@misc{indiciae9cd5431b40dc,
  title = {Mineral resources; potentials and problems},
  author = {Walden P. Pratt and Donald Albert Brobst},
  year = {1974},
  doi = {10.3133/cir698},
  url = {https://pubs.usgs.gov/publication/cir698},
  note = {Source identifier: cir698}
}